1. Field of the Invention
The present invention relates to reformulating polymer or wax bound military explosives and propellants into a useful form.
2. Brief Description of the Prior Art
A number of explosive compounds used in military explosives and propellants possess properties that are not desired in military warheads and in other military applications. To improve their properties, highly brisant explosives are often embedded in or coated with a curable plastic material or with a wax. When the explosive or propellant is coated with a wax the process is called phlegmatization. Other materials such as rubber can be added to impart specified mechanical properties like elasticity. The term plastic includes gelatinized liquid nitrocompounds of plasticine-like consistency.
Waste military explosives and propellants are a growing disposal problem as a result of world demilitarization. In the past, they have been disposed of by deep sea burial, open burning, open detonation or incineration.
For example, rocket motors have been dumped into the ocean off the continental shelf where the high specific gravity of the solid propellant causes the motors to sink rapidly. The rate at which the propellant leaches out under oceanic conditions is unknown, as are the likely products of hydrolysis. The environmental impact of deep sea burial and the cumulative effect of dumping large tonnages of explosives and propellants is therefore unknown.
In open burning, loose explosive or propellant materials or a complete rocket motor, for example, is placed on the ground or in a tray or pit which may be lined with a concrete pad. An explosive train leading to the material is used to initiate burning. The burning explosive or propellant creates a large updraft dispersing a plume of combustion products into the atmosphere.
The combustion products of open detonation are similar to those produced during open burning. Incineration is cleaner but requires special incinerators and safety considerations since explosives and propellants can burn with intense heat and some can explode. Emissions of HCl, NO.sub.x and HCN and particulates such as aluminum oxides, requires expensive air pollution control devices. The combustion products may be highly corrosive, thus affecting capital and maintenance costs.
Other disposal methods for destroying explosives or propellants include converting them into a less noxious form through chemical conversion, biodegradation, electrochemical oxidation, supercritical oxidation and so forth. All of these disposal methods involve high investment costs and/or may result in the same or different regulatory or environmental problems as deep sea burial, open burning, etc. In addition, destruction of the explosive or propellant (including conversion into a less noxious form for disposal) is contrary to the Resource Conservation and Recovery Act (RCRA).
Reclamation of the explosives or propellants as opposed to destroying them is in compliance with RCRA but reclamation requires the identification of a solvent which will dissolve the explosive or propellant out of the materials that are added to improve its properties. When the explosive or propellant is polymer bound, reclamation may not be possible when the polymer is too highly cross-linked.
One such reclamation method uses waterjets to wash out the explosive or propellant from the warhead or the like. The washed out material is passed over a vibrating screen which separates solids and liquids. Solid materials are placed in containers such as fiber drums and disposed of by open burning. The solvent is recirculated until the reclaimed explosive or propellant reaches a level at which the solvent is discharged into an open evaporation basin or treated in some other way (i.e., crystallization, etc.). In addition to the reclaimed material, the above reclamation process results an explosive-contaminated binder and an explosive-contaminated solvent, giving rise to a host of other disposal problems. Moreover, there is no guarantee that the reclaimed material will requalify to meet military specifications and in some cases it has no other legitimate customer.
There is a need for a process where the military explosive or propellant could be used without reclaiming it from the materials added to improve its properties. One proposed process uses military explosives or propellants as an extender in commercial explosives. In an oxygen-balanced explosive, the amount of oxygen present is just sufficient to oxidize all carbon to CO.sub.2 and all hydrogen to H.sub.2 O and any metals to their oxides with a minimum production of toxic NO.sub.x, CO and HCN. If there is insufficient oxygen to do this, the oxygen balance is negative. Excessive amounts of oxygen should be avoided because the amount of energy liberated is greatest at a slightly negative oxygen balance with explosives, for example, containing only C, H, N and O. Most military explosives and propellants, however, are oxygen deficient so that the full energetic potential of the material is not achieved when a military explosive or propellant is used as an extender. In addition, the mixture gives rise to toxic fumes such as CO, NO.sub.x and HCN when it is detonated and any chlorine in the explosive or propellant may end up in the form of chlorinated dibenzodioxins or dibenzofurans.